1. Related Applications
This application claims priority to two Japanese patent applications, (1) 2003-101427, filed Apr. 4, 2003; and (2) 2003-118048, which was filed Apr. 23, 2003, which are both hereby incorporated by reference.
2. Field of the Invention
This invention relates to a cartridge-type soldering iron capable of performing soldering operations and emitting inert gas, and more particularly, to a cartridge-type soldering iron capable of soldering operations in a constricted space.
3. General Background and State of the Art
As printed circuit boards are discarded, lead (Pb) embedded in the circuit board can release into the environment. The release of lead into the environment can lead to environmental hazards. To remedy this problem, some have developed soldering compounds that are free of lead. One of the drawbacks with lead free solder, however, is that the melting point of lead-free solder is 30° C. to 50° C. higher than the melting level of 210° C. to 232° C. of lead solder. This means that a soldering tip temperature of 350° C. or higher must be maintained in order to perform soldering operations with lead free solder. With such a high soldering tip temperature, flux in the solder can deteriorate, which can cause rapid oxidation in the soldering tip. As such, when lead free solder is used, the life of the soldering tip is shortened.
Various solutions to the above problems have been proposed, including the methods described in Japanese Utility Model Application Laid-Open No. H6-70962 and U.S. Pat. No. 6,247,631. The preferred method described in No. H6-70962 relates to a cartridge-type soldering iron where threaded solder is supplied automatically. This is accomplished by providing a soldering iron having a heating element with a bent top end, and a handle that intersects with the body of the heater and forcing the thread solder into the bent top end of the heating element. As such, the soldering iron disclosed in the '962 application cannot be applied to a cartridge-type soldering iron where the soldering tip and the handle are arranged in a straight line. In addition, to form a flow path for the inert gas, a cylindrical pipe attached to the heating element projects at an angle from the handle. This cylindrical pipe obstructs precise soldering operations, and it is difficult to precisely position the cylindrical pipe in order to maintain a uniform flow path for the inert gas. The supplied thread solder also hinders the soldering operation, so that it is generally not used in a printed circuit board with a high degree of concentration.
The '631 patent attempts to solve the shortcomings of the '962 application with a cartridge-type soldering iron where the soldering tip and the handle are arranged in a linear configuration. Projections are provided on an outer periphery of the heating element and the inner periphery of the pipe, and the heating element and the pipe are precisely positioned to provide a uniform flow path for the inert gas. However, the plurality of projections on the outer periphery of the heating element and the inner periphery of the pipe in the '631 patent are inherently inefficient. Accordingly, a more easily produced cartridge-type soldering iron is desirable. A cartridge-type Pb-free soldering iron with readily interchangeable soldering tips that can be replaced by the user without special tools is also highly desirable.